CN101163862B

CN101163862B - Turbine blade with a cover plate and a protective layer applied to the cover plate

Info

Publication number: CN101163862B
Application number: CN200680013189.1A
Authority: CN
Inventors: A·施雷; G·施瓦斯; A·德拉策尔
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2005-04-21
Filing date: 2006-01-20
Publication date: 2011-10-05
Anticipated expiration: 2026-01-20
Also published as: JP4874329B2; US20090022583A1; CN101163862A; EP1715140A1; JP2008538399A; WO2006111427A1; EP1871991A1; US8021120B2

Abstract

The invention relates to a turbine blade (16) with a cover plate (20) shaped onto the pan (18) of the blade. The aim of the invention is to provide a turbine blade of this type that, while having a high level of efficiency, is designed for a particularly reliable and safe operation in a turbine, particularly of a steam turbine (2). To this end, the invention provides that a protective layer made of an alternative material is applied to the surface of the cover plate (20) facing away from the pan (18) of the blade. The friction behavior with regard to a turbine component, particularly a sealing strip (30), which is opposite the protective layer (28), can be specifically influenced whereby enabling favorable emergency running properties to be provided in the event of rubbing.

Description

Have cover plate and be arranged on the turbine blade of the protective layer on this cover plate

Technical field

The present invention relates to a kind of turbine blade and a kind of steam turbine that is provided with a plurality of described turbine blades that is molded over the cover plate on the blade that have.

Background technique

The turbine blade of steam turbine often is provided with the cover plate that correspondingly is molded in the front on the blade.Usually the described turbine blade that correspondingly is merged into moving vane group or guide vane group so is arranged on the rotor or shell of described steam turbine, make vane group correspondingly in the side one of the overall formation of the outstanding cover plate that surpasses described blade around ring, so-called shroud.At this, attach troops to a unit in the cover plate wedging or the clamping so each other usually when mounted of the turbine blade of vane group, thereby can abandon other fastening piece or link between single cover plate.By the coupling of described turbine blade in annular shroud, suppressed very effectively because the vibration or the distortion of the single turbine blade that high dynamic load occurs.

The cover plate that correspondingly is merged into shroud of vane group be designed for since surpass blade tip in other words the secondary gap loss and the edge penalty that causes that flow of shroud be reduced to bottom line.For this reason especially the steam turbine full load in service be devoted to described shroud and and opposed shell of this shroud or rotor between as far as possible little gap width.On the other hand, should avoid scraping in running as far as possible.But especially in unsettled running just such as when starting or when the load conversion, participating in existing on the parts of work bigger because the danger of the relative length change that different thermal expansions causes, thereby under exception, still must reckon with the scraping phenomenon.For the expansion maintenance of potential contact position is as far as possible little and frictional force that also will occur under the contact situation thus are reduced to bottom line, used be fixed on described shroud or with the opposed shell of this shroud or metal bar or metal ring epitrochanterian, that along the circumferential direction stretch, just so-called sealing strip.If rotation and fixing parts compare planned more each other close, at first be that thin sealing strip contacts with opposed parts so in this case, the surface of wherein said two Contact Pair is scraping mutually in the friction zone that is restricted on the position usually.At least under the situation of disposable scraping or short time scraping, guarantee enough antifriction performances thus.

If but occur described running state more frequently, so described sealing strip correspondingly be arranged on the opposed turbine components of described shroud on-that is to say and be arranged on the shell (at moving vane shroud time) or be arranged on the rotor (at the guide vane shroud time)-situation under, exist the danger that continues the overall wearing and tearing of the described cover plate of infringement or described shroud.In this case, described sealing strip may " be nipped " in the described shroud dearly, and this is through after some times even can cause shroud almost completely to be degraded.The stability of the composite decking that original ring-type is surrounded significantly reduces because of the local fracture that wearing and tearing cause, this point has been encouraged the generation of blade vibration.During these external continuation wearing and tearing or when amplitude is too big, the fragment of the visible size of naked eyes or even all turbine blade will come off, fragment that then comes off or blade get rid of turbine blade or case member to ensuing turbine stage with very big kinetic energy.This will cause steam turbine to damage fully under extreme case.

Turbine blade with shroud is disclosed in FR-A-1470032.

Disclose a kind of Sealing that is arranged between the fixing and movable parts in US 2003/107181A1, wherein said inactive parts have grinding layer and movable parts are arranged according to the mode that soon touches this layer grinding layer.

Disclose a kind of turbine blade tip with lapped face in EP 1312760, wherein said lapped face comprises abrasive grains.

Grinding layer with high antioxidant is disclosed in US 2003/183529A1.

Summary of the invention

Therefore, task of the present invention is the turbine blade of a kind of the above-mentioned type of explanation, and this turbine blade is designed for reliable and safe especially operation having under the high efficiency situation.A kind of steam turbine of equipping described turbine blade will be described in addition.

Aspect turbine blade, this task solves by the feature of claim 1.

The present invention is based on such design at this, promptly steam turbine should be designed for so-called " elevated steam conditions " and move, to obtain high efficiency.Especially should load the steam of high as far as possible temperature to turbine blade.Be devoted to surpass 500 ℃ until about 700 ℃ vapor (steam) temperature at this.Corresponding, described turbine blade and the case member that is formed for the flow channel of steam are in addition made by exotic material.Consider described turbine blade especially with the bigger mechanical load of the moving vane of high speed rotating, the material that is used to make corresponding blade body should satisfy the highest requirement to mechanical stability and resistance to cracking under the high Operational Limits by this design setting.But for the manufacture cost of turbine blade is kept as far as possible little, this material should simultaneously also can be than being easier to process (such as by cast).In addition, for avoiding flow losses, the described shroud that the blade tip of vane group is coupled together and and the opposed turbine components of this shroud between the corresponding radial clearance of (that is to say under the situation at moving vane shroud and between the described turbine casing or) under the situation of guide vane shroud and between the rotor have as far as possible little width.Because under by the influence of the high running temperature of this design setting and since the deviation with about the temperature model of the medial axis symmetry of steam turbine that in this temperature model, may occur can cause the distortion of described rotor and/or shell and cause the gap shape and the perfect deviation of annular shape thus, so steam turbine is arranged in have maximum near the critical zone of limit in the time should can not get rid of in principle at least shroud and with opposed rotor of this shroud or shell between of short duration the contact.Or rather, under the scraping situation, also should guarantee enough antifriction performances for averting a calamity property turbo machine damages.Preferred described scraping process even allow again and again normal emerged in operation at turbo machine, and do not bring tangible consequence.

In addition, the present invention is based on such design, promptly the quality of described antifriction performance is by the frictional property the subject of knowledge and the object of knowledge decision between corresponding surface of contact.Except may be the performance of the liquid film that the steam particle by condensation that exists on the interface constitutes, the corresponding surfacing of two friction pairs also directly has influence on frictional behaviour, wherein not only be devoted to as far as possible little friction factor, and should consider the type of occurring wear when friction.

In this case, described interface-adhere to connection by the part form and subsequently the cracking that connects of solid so-called " adhesion wear " that cause be considered to harmful especially, this adhesion wear and material splash (Ausbruch) and the material transfer of transferring on the friction pair that contacts with the splash position are relevant.In other words: the particles agglomerate of degrading from one of them friction pair and can form bigger piece there on the surface of another friction pair, and these pieces have improved abrasive action.The material that is accumulated in this process owing to its wedge impacts rotor shaft.

Have bigger fragment and come off from fray when adhesion wear occurring, the mechanism of this just adhesion wear that self more and more strengthens should be avoided, and moves for a long time reliably with the steam turbine that guarantees to have the scraping process of having taken into account that occurs sometimes.For the intensity reason or to the manufacturing of turbine blade and the reason of workability that correspondingly is molded over the manufacturing of the cover plate on these turbine blades, preferred some specific materials that use, but these materials have disadvantageous frictional behaviour with respect to described with the opposed surface of shroud (the normally surface of metallic seal band) just.Therefore provide extra degrees of freedom so that influence friction pair targetedly on the surface of shroud in other words by being applied to corresponding cover plate by the protective layer that substitution material is made.That is to say that the protective layer of outside needn't be fulfiled support function, provide particularly advantageous friction and wear performance avoiding being specifically designed under the situation of adhesion wear with respect to corresponding friction pair but can replace especially.Consider obtainable advantage, can tolerate the manufacturing expense that increases a little fully at this.

For avoiding possible fracture position, the blade body strong load, that comprise blade and cover plate that especially bears of turbine blade is preferably made with the workpiece of unimodule.As the heat-resistant material that is used for described cover plate or whole blade body, can especially have the steel of 10% to 13% chromium content such as using steel.But, preferably use nickel-base alloy or cobalt base alloy base material as blade body as material high temperature resistant especially also corrosion resistant especially, that be suitable for vapor (steam) temperature up to 700 ℃.

The described lip-deep protective layer that is arranged on corresponding cover plate is made by a kind of so-called cobalt-based armouring alloy.The composition of alloy this specially with high-fire resistance and wear resistance and with corresponding (potential) friction pair that is to say especially with a kind of and corresponding opposed metallic seal band of shroud acting in conjunction under provide favourable frictional behaviour to be as the criterion.Be regarded as in this following situation favourable, if two surface of contact in friction each other under the situation of less metal dust particle detachment under the scraping situation, and do not cause material transfer or cause bigger material piece splash.This with microscope just observable tiny mill dirt easily along with the steam of percolation from turbo machine is taken out of and transferred out from flow channel.

Under concrete condition, the composition of the armouring alloy of described formation protective layer must be coordinated with the material of described opposed sealing strip.In the framework of comparative test, it is favourable that common a kind of alloy confirms, this alloy is except cobalt (chemical symbol: Co) also have the composition of nickel (Ni), iron (Fe), chromium (Cr), manganese (Mn), carbon (C), silicon (Si) and tungsten (W).Composition (data declaration is a unit with the weight percent point) is as follows:

Ni

Fe

C

Cr

Mn

Si

W

Maximum 3

1.1-1.2

28

1.0-1.1

4.5

Also common described armouring alloy under trade mark " Stellite " by Deloro Stellite register of company.Especially preferably in the framework of new departure, use material rate " No. the 6th, Stellit ".

The preferred described hard alloy that is used for carrying out armouring to shroud is set to described shroud surface by a kind of overlaying method, and carries out material with base material thus and be connected.At this, described coating material is such as being set on the workpiece surface with the built-up welding by one or more layers welding bead of a kind of gas welding process, arc-welding method or shielding gas welding process.Equally also can use so-called plasma arc powder surfacing or laser beam built-up welding.Employed hardfacing alloy adds as silk, rod, powder or cream mud by method selected.Because the common smooth and smooth surface of described alloy, especially can come in this way well to the cover plate of turbine blade in other words shroud apply.

With opposite with the painting method of the scheme as an alternative that it is contemplated that such as the cover coat that is in the micrometer range that gas phase spraying plating, surface hardening, nitriding or boronising can produce, so the protective layer that produces has significant preferred general 1 millimeter or bigger thickness.Guarantee the long working life of described protective layer thus, wherein said protective layer still exists after sealing strip opposed with it weares and teares fully in principle, and does not damage the base material of described cover plate.

A kind of preferably as an alternative in the design for scheme scheme, hard material layer is set as lip-deep protective layer at the blade dorsad of described cover plate.Usually natural to one skilled in the art hard, needn't stand any heat treatment and be called as hard material with the material that hardens.The use of described hard material has such advantage; even promptly also very little by its wearing and tearing after the use of long period of its protective layer of making, and replace under the contact situation described compare with protective layer soft sealing strip targetedly described steam turbine with opposed shell of cover plate or rotor on through frayed.Therefore only must usually change described sealing strip.

The hard material that has openly had covalent bond, ionic bond or metallic bond.Diamond be have covalent bond hard material famous representative material and also be the hardest naturally occurring mineral simultaneously.Hard material with ionic bond is such as comprising aluminium oxide or chromium oxide, but pottery also belongs to row wherein.

Be provided for to corresponding cover plate in other words the coating protected of shroud preferably make by a kind of hard material of metal.Consider its frictional behaviour and because its machinery and thermostability are preferably used carbide and the nitride that is formed by transition metal at this.As particularly preferred hard material chromium carbide or titanium nitride or boron nitride are set.

Preferably the plasma spray metallization by also can handling especially effectively on industrial scale, flame spraying or produce hard material layer by PVD-method (physical vapor deposition), the salient point of such hard material layer are good bond strength on the metal background of cover plate and high-purity and are special clearly that determine and undoped surface property thus.The thickness of described hard material thin layer is usually in micrometer range.

Corresponding individually being set on the described cover plate before described protective layer can be installed on the rotor of steam turbine or the shell at the cover plate with turbine blade.Yet when applying the hard material thin layer (such as by the PVD method or by plasma spray metallization or similar approach), especially also (" Si Tailite cobalt-chromium-tungsten alloy method (Stellitieren) ") especially preferably makes that described cover plate by the turbine blade of installing already forms and is lathed round-shaped shroud and stand coating on the whole when carrying out armouring by built-up welding.Therefore the described necessary process step of protective layer (described process step may comprise pretreatment and reprocessing) that applies correspondingly is applied on the section that comprises a plurality of cover plates of described shroud.Hundreds of short welding beads are opposite with using on single blade, and only that is to say in installment state concerning built-up welding should be with the welding bead pull and stretch of smaller length to the circumference of described shroud.The method of described present setting is quicker and safer aspect process engineering, and since joint and discontinuities (An-und Absetzstellen) so better quality still less is provided.Maintenance that it also is suitable for having worn and torn in special mode or uncoated old shroud still or reinforcement.

Preferably grinding layer is applied on the described hard material layer.When being in contact with one another, described metallic seal band can at first add before its hard material layer below being in contacts in the softer layer of that is to say of this layer grinding.Described sealing strip can be not impaired when contacting with described grinding layer, but keep its original dimensions and seal action.In other words: because the surface profile of described grinding layer be in sealing strip top or that slip away be complementary (described grinding layer " distortion when needed "), so can consciously the radial clearance between parts rotation and fixing of described steam turbine be kept very little, this helps to realize high efficiency.

Illustrated turbine blade is the constituent element of steam turbine preferably.But it also can be used in the gas turbine.Correspondingly a plurality of described turbine blades are merged into vane group at this; wherein said attaching troops to a unit in the correspondingly so moulding and so arranging to each other of the cover plate of the turbine blade of vane group, make its constitute around, the shroud that covered by the protective layer of being made by substitution material.Under the situation that relates to the moving vane group, preferably be provided with a plurality of along the sealing strip of circumference on the inboard of described turbine casing according to coated surperficial opposed mode with affiliated moving vane shroud.Under the situation that relates to the guide vane group, preferably according on the outside of turbine shaft, arranging described sealing strip with the coated surperficial opposed mode of described guide vane shroud.

Preferred such sealing strip comprises a plurality of bands by bending of circular segments shape or moulding, and described band is made by a kind of steel resistant to elevated temperatures, cold-formable, especially makes by a kind of martensite or austenitic steel or by a kind of nickel-base material.Listed in the form below some suitable examples and chemical name thereof, the name of an article (if any) with and the international material numbering:

Chemical name	Material number	The name of an article
			X20CrMo13KG	?1.4120	?
X22CrMoV12-1KG	?1.4923	?
			X6CrNiMoTi17-12-2	?1.4571	?
X6NiCrTiMoVB25-15-12	?1.4980	A286

NiCr23Co12Mo

?2.4663

Inconel (Inconel) 617

?NiCr20Ti

?2.4951

Nimonic (Nimonic) 75

Replace to embed (that is to say and in its bearing, solidify) or directly put into (" being involved in ") sealing strip of fixed groove accordingly with stamping material (Stemm-Material), also can be provided be molded over or be tightened on the opposed turbine components of described shroud (rotor or shell or its part bow-shaped section) on the sealing rib.Described sealing strip or the sealing rib also can be configured in case of necessity around helical.

The advantage that realizes with the present invention especially is, by protective layer is applied to this way obtains on the corresponding cover plate material select with surface structuration aspect degrees of freedom be used for influencing energetically frictional behaviour targetedly with respect to the sealing strip that may contact with described cover plate.Radial clearance between parts rotation and fixing of steam turbine can be provided with forr a short time, because there is comparatively favourable antifriction performance when contact.Thus with avoid contacting this situation in all cases by the safety clearance of arranging very roomyly in other words by enough big radial clearance and compare and can realize better efficient.The shroud base material that concerning the stability of described ring-type shroud structure, plays a decisive role pass through the protective layer that applied in other words separate layer prevent the wearing and tearing that cause by friction and/or corrosion.As long as described protective layer has enough hardness, that just can be transferred to wear phenomenon on the described sealing strip in a side to the full extent, and described sealing strip then can be changed with comparatively simple methods often.

Description of drawings

By means of accompanying drawing different embodiments of the invention are explained in detail below.Accompanying drawing illustrates:

Fig. 1 is the schematic representation in the longitudinal section (intercepting part) of steam turbine,

Fig. 2 is the cross section by the steam turbine of Fig. 1, and this steam turbine has many turbine blades that are merged into vane group, wherein the cover plate of single turbine blade be gathered into around shroud,

Fig. 3 is the detailed view that is provided with the turbine blade of cover plate in the steam turbine by Fig. 1, wherein is provided with the protective layer of being made by substitution material on described cover plate,

Fig. 4 is the turbine blade that has cover plate in a kind of mode of execution of scheme as an alternative, and this cover plate then has protective layer, and

Fig. 5 is the turbine blade that has cover plate at another kind as an alternative in the mode of execution of scheme, and this cover plate then has protective layer.

Identical parts are represented with identical reference character in institute's drawings attached.

Embodiment

Fig. 1 shows steam turbine 2, and this steam turbine 2 has a plurality of rotatable moving vanes 6 that are connected with turbine shaft 4.Described moving vane 6 correspondingly is arranged on the described turbine shaft 4 by the garland shape, and forms a plurality of moving vane groups thus.In addition, described steam turbine 2 comprises a plurality of fixing guide vanes 8, and described guide vane 8 is fixed on the turbine casing 10 of described steam turbine 2 under the situation that forms the guide vane group by the garland shape equally.Vaporish working medium M flows through from the flow channel 12 that is limited by turbine shaft 4 and turbine casing 10 of described steam turbine 2 along being parallel to main flow direction that medial axis 14 extends, wherein be heated to the temperature more than 540 ℃ and be in release under the situation of doing work, and the pulse transmission that passes through in this process on the described moving vane 6 drives described turbine shaft 4 such as the steam under the high pressure of 250bar at input side.In contrast, 8 of described guide vanes are used for the delivery working medium M that flows between moving vane group continuous before and after corresponding two flow directions along described working medium M are looked each other or the movable vane loop.Guide vane 8 rings that a pair of front and back each other link to each other or guide vane group and moving vane 6 rings or moving vane group are also referred to as turbine stage at this.

Fig. 2 shows the intercepting part of the cross section that extends perpendicular to medial axis 14 of described steam turbine 2, and a plurality of as can be seen turbine blade 16-are a plurality of moving vanes 6 in this case on this steam turbine 2.The described moving vane 6 that is fixed on the turbine shaft 4 by the garland shape correspondingly has on the blade 18 that is molded over described contoured on the end to the outside of radial finger just in its front and cover plate 20 that give prominence in the side.The cover plate 20 of per two adjacent moving vanes 6 contacts with each other.That is to say that described cover plate 20 clamps each other when being installed to described moving vane 6 on the turbine shaft 4, thereby forming the circular integration body of sealing, so-called shroud 22.Suppress the distortion of individual blade 18 or the vibration of blade tip thus effectively.Aspect aerodynamics, be to be worth pursuing though adjacent cover plate abuts against each other in its whole axial stretching, extension (along the direction of turbine shaft), always not accomplished for the design reasons this point.That is to say only direction of extension closure (as shown in FIG. 2) vertically on a position of described shroud when " line contact " occurring in running, this line contact is complete enough actually.

The circular outer perimeter of described shroud 22 and described turbine casing 10 and the opposed inboard of described circumference between radial clearance 24 keep as far as possible little on the one hand, be used for (secondary flowing causes because working medium M surpasses that blade tip surpasses shroud 22 in other words) gap loss is reduced to bottom line.On the other hand described radial clearance 24 is designed to so wide size, the radius fluctuation that cause by heating or that cause by mechanical influence that makes that certain occurs usually in the running of steam turbine 2 or and round-shaped between deviation can not cause the scraping of the shroud 22 that rotates.

Except described moving vane 6, the guide vane 8 of described steam turbine 2 has the cover plate 20 that is molded on the corresponding blade 18, described cover plate 20 forms the shroud 20 of attaching troops to a unit in corresponding guide vane group generally at it, guide vane shroud just in this case, this guide vane shroud is spaced apart with described turbine shaft 4 by radial clearance 24 in similar (but not being shown specifically here) mode.

The efficient of described steam turbine 2 is optimized by the setting of especially little radial clearance, yet has also improved the possibility of scraping process thus.However in order to guarantee high operational reliability, make the turbine blade 16 of described steam turbine 2 special to provide favourable antifriction performance to be as the criterion.By means of the moving vane that in Fig. 3, in details drawing, exemplarily illustrates 6 this is made an explanation.But all relevant therewith considerations can be overlapped on the guide vane 8 of using described steam turbine 2 without a doubt.

The turbine blade 16 that schematically illustrates in Fig. 3, be configured to moving vane 6 has the cover plate 20 that is molded on the blade 18, the wherein said blade body of blade 18 and cover plate 20 that comprises is made by the workpiece of unimodule for realizing high mechanical stability and temperature stability, and this workpiece is then made by nickel-base alloy.Described cover plate its described dorsad blade 18, just on a side of the turbine casing 10 of described steam turbine 2, be provided with the protective layer of making by chromium carbide 28 that applies by the plasma spray metallization.According to opposed with described protective layer 28 and by radial clearance 24 and described protective layer 28 isolated modes, in the inboard upper edge of described turbine casing 10 circumference the sealing strip of forming by a plurality of ring segments 30.If described sealing strip 30 is owing to temporarily contact with the described shroud 22 that is formed by whole cover plates 20 of vane group in other words with cover plate 20 wherein on the position at its circumference in the thermal expansion process of steam turbine 2 inside, the base material of cover plate 20 just prevents to wear and tear by described protective layer 28 so accordingly.Bigger hardness by the described protective layer of making by hard material (here in this embodiment by chromium carbide) 28; the described sealing strip 30 that at first weares and teares targetedly and reliably when being in contact with one another makes sealing band 30 can not enter original cover plate 20 in other words in the shroud surface.

Shown in Figure 4, the similar of turbine blade 16 that can be configured to moving vane 6 or be configured to guide vane 8 has wherein only applied the extra grinding layer 32 of one deck in disclosed turbine blade from Fig. 3 on described protective layer 28.The shroud 22 of dual-coating and and these shroud 22 opposed sealing strips 30 between radial clearance 24 design so for a short time at this; thereby in the running of steam turbine 2, adjust layout shown in Figure 4; though be grinding in the described grinding layer 32 at sealing strip 30 described in this layout, in general also not be in following hard material protective layer 28 and contact.Realize on the one hand the splendid sealing effect of described flow channel 12 thus, wherein the frictional loss of being worth mentioning does not appear in the performance of the appropriate selection by described grinding layer 32 on the other hand.The described protective layer of being made by hard material 28 is being protected described shroud 22 as beforely when described gap clearance occurs than great fluctuation process, and guarantees acceptable antifriction performance at this.

On the guide vane 8 shown in Figure 5, the described in other words shroud 22 that is formed by all cover plates 20 of guide vane group of described cover plate 20 has the ladder that the ladder with described opposed turbine shaft 4 is complementary, thereby forms the branched bottom 34 of the mazy type bending of described flow channel 12 betwixt.Described branched bottom 34 obtains sealing by described along the sealing strip 30 of circumference on turbine shaft 4, has wherein correspondingly stayed the radial clearance 24 that fluctuation is arranged on its width in the running of described steam turbine 2.For particularly advantageous antifriction performance is provided under the scraping situation, the described cover plate of being made by a kind of resistant to elevated temperatures material 20 shroud 22 is in other words being covered with described sealing strip material protective layer 28 that coordinate, that made by a kind of substitution material aspect its friction and the polishing machine in example in front.Described protective layer 28 can be made by a kind of hard material again.But in this case, this protective layer 28 is to be added to stellite layer (Stellitschicht) on each local surfaces that forms described ladder by built-up welding, and its original thickness is about 1 millimeter, but has reduced some a little by finishing.

To one skilled in the art, any is arranged is conspicuous, promptly describedly can change in many ways by means of the embodiment shown in the accompanying drawing, and do not abandon important for purposes of the invention scheme in this process.Therefore such as also ladder being set on moving vane shroud, perhaps described ladder can have the profile different with Fig. 5.At last, also isolated seal ring of a plurality of axial directions along described steam turbine 2 or sealing strip 30 can be merged into one group of sealing strip 30, this group sealing strip 30 and corresponding shroud 22 are opposed and realized multi-sealed thus.

Claims

1. the turbine blade (16) that has the cover plate (20) that is molded on the blade (18); wherein on the surface of the described dorsad blade (18) of described cover plate (20), apply the protective layer of making by substitution material (28); wherein said protective layer (28) is made by cobalt-based armouring alloy, it is characterized in that: described armouring alloy comprises the nickel of maximum 3% weight percentage; the iron of maximum 3% weight percentage; the carbon of 1.1% to 1.2% weight percentage; the chromium of 28% weight percentage; the manganese of 1.0% to 1.1% weight percentage; the tungsten of the silicon of 1.0% to 1.1% weight percentage and 4.5% weight percentage.

2. by the described turbine blade of claim 1 (16), make by the workpiece of unimodule comprising the blade body of blade (18) and cover plate (20).

3. by claim 1 or 2 described turbine blades (16), its cover plate (20) is made by nickel-base alloy or cobalt base alloy.

4. by the described turbine blade of claim 1 (16), wherein said protective layer (28) is applied on the described cover plate (20) by built-up welding.

5. by the described turbine blade of claim 1 (16), the corresponding armouring alloy of wherein said protective layer (28) has about 1 millimeter or bigger thickness.

6. by the described turbine blade of claim 1 (16), the corresponding armouring alloy of wherein said protective layer (28) is connected with described cover plate (20) material.

7. by the described turbine blade of claim 1 (16), wherein said turbine blade (16) is used in the steam turbine (2).

8. by the described turbine blade of claim 6 (6), the corresponding armouring alloy of wherein said protective layer (28) is connected with described cover plate (20) material by welding.

9. have a plurality of correspondingly be merged into vane group, by the steam turbine (2) of each described turbine blade (16) in the claim 1 to 8.

10. by the described steam turbine of claim 9 (2), wherein attach troops to a unit in the correspondingly moulding and relative to each other arranging of the cover plate (20) of the turbine blade (16) of vane group, make its form around shroud (22).

11. by the described steam turbine of claim 10 (2), wherein said vane group is the moving vane group.

12., wherein be provided with a plurality of along the sealing strip (30) and/or the sealing rib of circumference on the inboard of the turbine casing (10) of described steam turbine (2) according to surperficial opposed mode through applying with described shroud (22) by the described steam turbine of claim 11 (2).

13. by the described steam turbine of claim 12 (2), wherein said vane group is the guide vane group.

14., wherein be provided with a plurality of along sealing strip (30) on the turbine shaft (4) of circumference in described steam turbine (2) and/or sealing rib according to surperficial opposed mode through applying with described shroud (22) by the described steam turbine of claim 13 (2).

15. by claim 12 or 14 described steam turbine (2), wherein sealing strip (30) comprises the metal band of a plurality of circular segments sigmoids.

16. be used to make the method for steam turbine; this steam turbine have a plurality of correspondingly be merged into vane group, by each described turbine blade (16) in the claim 1 to 8; wherein attach troops to a unit in the correspondingly moulding and relative to each other arranging of the cover plate (20) of the turbine blade (16) of vane group; make its form around shroud (22), wherein said protective layer (28) just is applied on the described shroud (22) after going up described turbine blade (16) being installed in turbine shaft (4) or turbine casing (10).

17. by the described method of claim 16; wherein said protective layer (28) correspondingly is applied in a plurality of process step on the section associated with each other described shroud (22), that formed by a plurality of cover plates (20), wherein correspondingly whole section is processed or is handled in each process step.

18., wherein apply cobalt-based armouring alloy by built-up welding by the described method of claim 17.